Atomic Theory LEQ (presentation one)
Aristotle and Democritus
Atom existed, no internal pieces were yet discovered
O shaped
John Dalton
Around the 1800s, helped propelled the atomic theory.
Verified Atoms (In an O shaped)
[Vocab]
Atom: The smallest unit of a chemical element, made up of a nucleus surrounded by electrons.
J.J. Thompson
"Plum pudding model" Discovered that atoms are able to split up atoms.
The model showed circles in the original model.
Robert Milikan
Verified the negative charge on an atom (-)
Rutherford
Came up with the idea of a nucleus in the atomic model.
Like a small o in a big O.
Neils Bohr
He added in the idea of energy levels for the electrons.
Along with electrons being outside the atom.
James Chadwick
Neutrons in the nucleus, still has electrons rotating outside the atom.
Tim & Graeme
Developed the quantum theory.
Electrons in organized chaos.
Atomic Mass (mass Number)
The average of all the masses of the naturally occurring isotopes of an element. The mass number is the rounded atomic mass. It is the number of protons and neutrons found in an atom.
[Mini-Vocab]
Isotope: Is every existing type of element with a different number of electrons.
Atomic Number
The number of protons in the nucleus of an atom.
FYI review
Number of Protons - same as the atomic number
Number of Electrons - same as the atomic number and the number of protons
Number of neutrons - Found by subtracting the atomic number from the mass number
Example: Florine (atomic number is 9)
of Protons - 9
of Electrons - 9
of Neutrons - (19 - 9) = 10
Quantum Theory
This theory replaced Bohr because his energy levels only worked for hydrogen.
The quantum theory uses complex mathematical equations to describe waves.
The model predicts quantized energy levels of electrons. It depends on the probability of finding an electron in a certain position.
This categorized the 7 energy levels into 4 orbitals.
Orbitals
Area where an electron can be found.
There are four orbitals: S,P,D,F
The orbitals are filled based on the location of the electrons on the periodic table.
S-Orbitals
Given a 3-D figure, the S-orbital would look like a sphere.
It can hold a maximum of 2 electrons - one pair of electrons.
S-orbitals will occur in all 7 energy levels.
P-Orbitals
Electrons begin filling the P-orbitals in the 2nd energy level after filling the 2s-orbital.
It can hold a total of six electrons - three electron pairs.
The shape of each of the P-orbitals look like a dumbbell. (Like a 3-D infinity shape)
D-orbitals
Electrons begin filling the D-orbitals in the 3rd energy level, after filling the 4s orbital.
The orbitals will hold 10 electrons - 5 electron pairs.
The 3-D shape of the D-orbital is 4 X-shapes with a life-saver around the center.
F-Orbitals
The occur in the 4th energy level after filling the 6s orbital.
The F-orbitals can hold 14 electrons - 7 electron pairs.
The electrons are in such chaos that there is no set shape to describe them.
Electron Configurations
A visual way to write how the electrons fill the orbitals.
The orbitals fill as you flow left to right and top to bottom on the periodic table: 1s, 2s, 2p, 3s, 3p, 4p, etc
Use of Bohr's Model
While Bohr's model only worked for the Hydrogen atom, his energy ideas are still used.
Electrons are in energy levels and can move energy levels when the electrons become energized. (quantized)
[Vocab] Energy Levels of an Atom.
- Bohr proposed the electrons can only reside in an energy level.
- The lowest energy level is closest to the nucleus.
Ground State - when electrons are in the lowest possible energy level.
Quantum - Amount of Energy needed to jump energy levels (particular energies given).
Excited State - When an electron has been quantized (given particular energy), it leads to waves of light.
[Movement of electrons - if an electron goes into an atom, the atom gets excited, if an electron fires out of an atom the atom is "De-excite"]
Calculations
E=hc / λ
energy (eV) or (Joules)
h=.63 x 10∧-34 Joules/Hertz
c=2.0 x 10∧8 m/s
Sample Calculation
- Calculate the frequency and energy of light waves that have a λ = 17.3 nanometers. What type of light wave is this?
v=c/λ= 3.0x10∧8m/s x 1x10∧9nm = 1.73 x 10∧16 l/s
17.3nm 1m
E=hv=
6.63x10∧34 J/Hz x 1.37 x 10∧16Hz = 1.15 x10∧-17 J
Trends In the Periodic Table
When studying the periodic table one can tell may things about an element just by its location on the table. These trends help scientists identify new elements and understand why an element has different properties.
Atomic Radius
Atomic radius within a group increases as one moves vertically down the periodic table.
Atomic radius within a period decreases as one moves horizontally right across the periodic table.
Ionization Energy
The energy required for elements within a group decreases as one moves vertically down the periodic table.
The energy required for elements within a period increases as one moves horizontally right across the periodic table.
(Top right hardest to remove electrons, bottom left easiest to remove electrons)
Shielding Effect
A decrease in the attractions of the outer electrons (valence electrons) to the positively-charged nucleus.
Increases as one moves vertically down the periodic table.
It remains constant as you move right across the periodic table because the electrons aren't being added to a new energy level.
- As you move down the periodic table there are more electrons inside and elements. This creates less of an attraction to the valence electrons. (the electrons in the lower energy levels are taking up too much of the nucleus' attention).
Electronegativity (EN)
How strong the bonds are within the compound.
Decreases as you move down the periodic table because the energy levels are growing.
Increases as you move right across the periodic table because more p+ are added to the nucleus allowing for more electrons.
- F is the most electronegative elements at 4.0 and Francium is the least at 0.7
Electron Affinity
A measure of the energy change that occurs as an electron is added to an atom.
Has the same trends as electronegativity for the same reasons (what you wrote on the previous slide).
Atomic Mass (Mass Number Again)
The average of all of the masses of the naturally occurring isotopes of an element.
The mass number is the rounded atomic mass. It is the number of protons and neutrons found in an atom.
Atomic Mass Units (AMU)
The mass number is the mass of both the protons and neutrons, not the total mass.
Scientists developed a unit to compare all atoms.
1 amu - 1.66x10(exponent to the -24) grams ( 1/12 the mass of carbon-12)
Average Atomic Mass on the PT
When you read the mass on the PT, the units are amu
Cu = 63.55 amu
These average atomic masses are the average of the atomic masses of the isotopes occurring in nature.
Amu when single atom; grams when larger amounts of materials.
Calculating amu
Scientists use the % of existence of isotopes multiplied by the mass all totaled to get the mass.
Ex: Cu-63 exists 69.17% of the time yielding a moss of 62.94 amu and Cu-65 exists the other 30.83% of the time with a mass of 64.93 amu. Together they create the amu of Cu. = (0.6917 x 62.94 amu) + (0.3083 x 64.93 amu) = 63.55 amu
Valence Electrons - Number in s & p orbitals in that period, skip d/f orbitals. Same groups always have the same amount of valence electrons.
Group # = valence electrons number; max valence electrons is eight. H and He exception in Octet. (only 2)
Positive Ions
Negative Ions
Left hand side
right hand side
Group I, II, III
gave away come
electrons
Ca^+2: Calcium
Group IV, V, VI, VII, VIII
Taking in Electrons
O^-2: oxide ion
Ionic Bonds
Oppositely charged ions attract and bond to each other. The compounds become known as salts.
In Example: The attraction of Na^+1 ion to a Cl^-1 ion forms the compound commonly known as table salt - Sodium Chloride.
Writing Ionic Formulas
Write the Cation and anion from the name - Lithium Oxide Li^+1 O^-2
Switch the charges to become subscripts. Li v2 O (the 2 is a subscript to the Li)
Reduce if like charges or common multiples (+2, -2 becomes 1:1, +4,-2 becomes 2:1)
Calculating the percent that an element exists within a compound.
Essentially you are giving each element a grade on the participation with in a compound.
Sample H2O
1. Mass of elements
a. H: 2*1.01 = 2.02g
b. O: 1*15.99= 15.99g
2. Mass of Compound: 2.02 + 15.99g =18.01g
3. Percent H: 2.02/18.01 = .112 x100 =11.2%
4. Percent O: 15.99g/18.01 = .8878 x 100 = 88.78% Calculating the % of an element
If we recover 12.31g of water after distillation, how many g of O are present?
- Using the 88.78% from above, (that shows the amount of oxygen that makes up water), just find what is 88% of 12.31g, using the remaining grams in the hydrogen's weight.
Working From % to Formula
We can also work backwards to determine the formula of a compound. This is called the empirical formula. It gives the lowest whole-number ratio of the elements in the compound.
Steps to doing this formula
When given a problem assume that you have 100g total (like %, making it easier) 25.4% = 25.4 g.
Calculate the moles of each element.
Divide the moles of each element by the smallest mole number to get the ratio. (Round to the nearest 0.5)
Multiply ratio by 2 if you have a 0.5 ratio.
Write the formula using the whole number ratio.
Sample Problem
A compound is analyzed and found to contain 25.9% N and 74.1% O. What is the empirical formula of the compound?
25.9g N x (1 mol N/14.0g) = 1.85 mol N
74.1g O x (1 mol O/15.99g) = 4.63 mole O
Ratio: 1.85/1.85 : 4.63/1.85 = 1:2.5
Whole Number 2(1:2:5) = 2.5
Formula: N2 O5 (Keep the formula steps in order left to right)
Hydrates
Compounds that have water trapped in them.
The water is trapped during a cooling process.
Formula: CuSO₄ ∙ 5H₂O
Naming: Copper II Sulfate pentahydrate (Prefix comes after the "Dot")
- More examples: copper sulfate trihydrate (CuSO4∙ 3H2O) is blue, and anhydrous copper sulfate (CuSO4) is white. (Has color changes) Examples
Aristotle and Democritus
- Atom existed, no internal pieces were yet discovered
- O shaped
John Dalton- Around the 1800s, helped propelled the atomic theory.
- Verified Atoms (In an O shaped)
[Vocab]- Atom: The smallest unit of a chemical element, made up of a nucleus surrounded by electrons.
J.J. Thompson- "Plum pudding model" Discovered that atoms are able to split up atoms.
- The model showed circles in the original model.
Robert Milikan- Verified the negative charge on an atom (-)
Rutherford- Came up with the idea of a nucleus in the atomic model.
- Like a small o in a big O.
Neils Bohr- He added in the idea of energy levels for the electrons.
- Along with electrons being outside the atom.
James Chadwick- Neutrons in the nucleus, still has electrons rotating outside the atom.
Tim & GraemeAtomic Mass (mass Number)
The average of all the masses of the naturally occurring isotopes of an element. The mass number is the rounded atomic mass. It is the number of protons and neutrons found in an atom.
[Mini-Vocab]
- Isotope: Is every existing type of element with a different number of electrons.
Atomic NumberThe number of protons in the nucleus of an atom.
FYI review
- Number of Protons - same as the atomic number
- Number of Electrons - same as the atomic number and the number of protons
- Number of neutrons - Found by subtracting the atomic number from the mass number
Example: Florine (atomic number is 9)Quantum Theory
- This theory replaced Bohr because his energy levels only worked for hydrogen.
- The quantum theory uses complex mathematical equations to describe waves.
- The model predicts quantized energy levels of electrons. It depends on the probability of finding an electron in a certain position.
- This categorized the 7 energy levels into 4 orbitals.
Orbitals- Area where an electron can be found.
- There are four orbitals: S,P,D,F
- The orbitals are filled based on the location of the electrons on the periodic table.
S-Orbitals- Given a 3-D figure, the S-orbital would look like a sphere.
- It can hold a maximum of 2 electrons - one pair of electrons.
- S-orbitals will occur in all 7 energy levels.
P-Orbitals- Electrons begin filling the P-orbitals in the 2nd energy level after filling the 2s-orbital.
- It can hold a total of six electrons - three electron pairs.
- The shape of each of the P-orbitals look like a dumbbell. (Like a 3-D infinity shape)
D-orbitals- Electrons begin filling the D-orbitals in the 3rd energy level, after filling the 4s orbital.
- The orbitals will hold 10 electrons - 5 electron pairs.
- The 3-D shape of the D-orbital is 4 X-shapes with a life-saver around the center.
F-Orbitals- The occur in the 4th energy level after filling the 6s orbital.
- The F-orbitals can hold 14 electrons - 7 electron pairs.
- The electrons are in such chaos that there is no set shape to describe them.
Electron ConfigurationsUse of Bohr's Model
[Vocab] Energy Levels of an Atom.
- Bohr proposed the electrons can only reside in an energy level.
- The lowest energy level is closest to the nucleus.
[Movement of electrons - if an electron goes into an atom, the atom gets excited, if an electron fires out of an atom the atom is "De-excite"]
Calculations
Sample Calculation
- Calculate the frequency and energy of light waves that have a λ = 17.3 nanometers. What type of light wave is this?
v=c/λ=
3.0x10∧8m/s x 1x10∧9nm = 1.73 x 10∧16 l/s
17.3nm 1m
E=hv=
6.63x10∧34 J/Hz x 1.37 x 10∧16Hz = 1.15 x10∧-17 J
Trends In the Periodic Table
Atomic Radius
- Atomic radius within a group increases as one moves vertically down the periodic table.
- Atomic radius within a period decreases as one moves horizontally right across the periodic table.
Ionization Energy- The energy required for elements within a group decreases as one moves vertically down the periodic table.
- The energy required for elements within a period increases as one moves horizontally right across the periodic table.
(Top right hardest to remove electrons, bottom left easiest to remove electrons)Shielding Effect
- A decrease in the attractions of the outer electrons (valence electrons) to the positively-charged nucleus.
- Increases as one moves vertically down the periodic table.
- It remains constant as you move right across the periodic table because the electrons aren't being added to a new energy level.
- As you move down the periodic table there are more electrons inside and elements. This creates less of an attraction to the valence electrons. (the electrons in the lower energy levels are taking up too much of the nucleus' attention).Electronegativity (EN)
- How strong the bonds are within the compound.
- Decreases as you move down the periodic table because the energy levels are growing.
- Increases as you move right across the periodic table because more p+ are added to the nucleus allowing for more electrons.
- F is the most electronegative elements at 4.0 and Francium is the least at 0.7Electron Affinity
Atomic Mass (Mass Number Again)
Atomic Mass Units (AMU)
- The mass number is the mass of both the protons and neutrons, not the total mass.
- Scientists developed a unit to compare all atoms.
- 1 amu - 1.66x10(exponent to the -24) grams ( 1/12 the mass of carbon-12)
Average Atomic Mass on the PT- When you read the mass on the PT, the units are amu
- Cu = 63.55 amu
- These average atomic masses are the average of the atomic masses of the isotopes occurring in nature.
- Amu when single atom; grams when larger amounts of materials.
Calculating amuConversion Factors
- Avagadro's Number = 6.022x10e23 atoms/molecules
--------------------------------------------------1mole (positive)- Molar Mass: = atomic mass (g)
--------------------------------1mole (positive)Valence Electrons - Number in s & p orbitals in that period, skip d/f orbitals. Same groups always have the same amount of valence electrons.
Group # = valence electrons number; max valence electrons is eight. H and He exception in Octet. (only 2)
gave away come
electrons
Ca^+2: Calcium
Taking in Electrons
O^-2: oxide ion
- Oppositely charged ions attract and bond to each other. The compounds become known as salts.
- In Example: The attraction of Na^+1 ion to a Cl^-1 ion forms the compound commonly known as table salt - Sodium Chloride.
Writing Ionic Formulas- Write the Cation and anion from the name - Lithium Oxide Li^+1 O^-2
- Switch the charges to become subscripts. Li v2 O (the 2 is a subscript to the Li)
- Reduce if like charges or common multiples (+2, -2 becomes 1:1, +4,-2 becomes 2:1)
Determining Formulas MathematicallyPercent Composition
- Calculating the percent that an element exists within a compound.
- Essentially you are giving each element a grade on the participation with in a compound.
Sample H2O1. Mass of elements
a. H: 2*1.01 = 2.02g
b. O: 1*15.99= 15.99g
2. Mass of Compound: 2.02 + 15.99g =18.01g
3. Percent H: 2.02/18.01 = .112 x100 =11.2%
4. Percent O: 15.99g/18.01 = .8878 x 100 = 88.78%
Calculating the % of an element
- If we recover 12.31g of water after distillation, how many g of O are present?
- Using the 88.78% from above, (that shows the amount of oxygen that makes up water), just find what is 88% of 12.31g, using the remaining grams in the hydrogen's weight.Working From % to Formula
- We can also work backwards to determine the formula of a compound. This is called the empirical formula. It gives the lowest whole-number ratio of the elements in the compound.
Steps to doing this formulaSample Problem
Hydrates
- Compounds that have water trapped in them.
- The water is trapped during a cooling process.
- Formula: CuSO₄ ∙ 5H₂O
- Naming: Copper II Sulfate pentahydrate (Prefix comes after the "Dot")
- More examples: copper sulfate trihydrate (CuSO4∙ 3H2O) is blue, and anhydrous copper sulfate (CuSO4) is white. (Has color changes)Examples